This pair of images was acquired by MODIS on Aug. 23 over Montana and Idaho; each image is 60 by 60 pixels and a single pixel is 1 square kilometer. The image on the left was made using MODIS channel 20 (centered at 3.7 micrometers); this image approximates the capability of the NOAA Advanced Very High Resolution Radiometer (AVHRR) to detect fires and measure their intensities. The image on the right uses MODIS channel 21 (centered at 3.90 micrometers). Notice how MODIS channel 21 shows greater sensitivity to the temperatures of the fires, which can help fire scientists pin point where there are active flaming fires and where fires are less intense or smoldering. This is important because large smoldering fires can contribute heavy amounts of pollutants into the atmosphere, while active flaming fires are often where fire firefighters concentrate their efforts for containment and suppression. Source: MODIS Science Team, Rong Rong Li, NASA GSFC